Combinatorial Approach toMaterials Discovery

Ichiro TakeuchiDept. of Materials Science and Engineering and Center for Superconductivity Research

University of Maryland

Cover ofChemistry & Industry,October 1998

1IA

2IIA

3IIIB

4IVB

5VB

6VIB

7VIIB

8VIII

9VIII

10VIII

11IB

12IIB

13IIIA

14IVA

15VA

16VIA

17VIIA

180

H1

He2

Li3

Be4

B5

C6

N7

O8

F9

Ne10

Na11

Mg12

Al13

Si14

P15

S16

Cl17

Ar18

K19

Ca20

Sc21

Ti22

V23

Cr24

Mn25

Fe26

Co27

Ni28

Cu29

Zn30

Ga31

Ge32

As33

Se34

Br35

Kr36

Rb37

Sr38

Y39

Zr40

Nb41

Mo42

Tc43

Ru44

Rh45

Pd46

Ag47

Cd48

In49

Sn50

Sb51

Te52

I53

Xe54

Cs55

Ba56

La57

Hf72

Ta73

W74

Re75

Os76

Ir77

Pt78

Au79

Hg80

Tl81

Pb82

Bi83

Po84

At85

Rn86

Fr87

Ra88

Ac89

Unq104

Unp105

Unh106

Uns107

Uno108

Une109

Uun110

Ce58

Pr59

Nd60

Pm61

Sm62

Eu63

Gd64

Tb65

Dy66

Ho67

Er68

Tm69

Yb70

Lu71

Th90

Pa91

U92

Np93

Pu94

Am95

Cm96

Bk97

Cf98

Es99

Fm100

Md101

No102

Lr103

Making New Materials

Searching for the right combinationof elements

For example, superconductorHgBa2CaCu2O7

Parameters that Affect Properties of Materials

1. Compositions 4. Presence of Defects•identity of components•stoichiometry

2. Dopants 5. Microstructures•identity•concentration

3. Processing Conditions•temperatures•pressures

Rapid characterization and screening of

physical properties

Materials diagnostics

Synthesis of combinatorial libraries and

composition spreads

Focus: Electronic Thin Film Materials

Fabrication of libraries and spreadsCombinatorial PLD systems – metal oxide systemsCombinatorial UHV sputtering system – metallic magnetic alloys

Combinatorial Materials Research at the University of Maryland

Rapid characterization toolsScanning SQUID microscopes – magnetic materialsScanning microwave microscopes – ferroelectric/dielectric materialsScanning X-ray microdiffractometer – smart materials, phase mappingNovel device libraries incorporating MEMS, etc.

Quaternary Masks

A B

C ED

Quaternary Masking

Ba

Quaternary Masking: 1st mask, 1st position

Ca

Quaternary Masking: 1st mask, 2nd position

Sr

Quaternary Masking: 1st mask, 3rd position

Pb

Quaternary Masking: 1st mask, 4th position

BaPb

Sr Ca

Ba

Quaternary Masking: after 1st mask

BaPb

Sr Ca

BaZr

Zr

Zr

Zr

Quaternary Masking: 2nd mask, 1st position

BaPb

Sr Ca

BaTa

Ta

Ta

Ta

Quaternary Masking: 2nd mask, 2nd position

BaPb

Sr Ca

Ba

Nb

Nb Nb

Nb

Quaternary Masking: 2nd mask, 3rd position

BaPb

Sr Ca

BaTi

Ti Ti

Ti

Quaternary Masking: 2nd mask, 4th position

BaZrO3

CaNb2O6

CaTiO3

BaNb2O6

BaTiO3

CaTa2O6

CaZrO3

BaTa2O6PbTa2O6

PbZrO3PbTiO3

PbNb2O6

SrTiO3

SrNb2O6 SrTa2O6

SrZrO3

A B

C ED

# depositions: 4 x n# combinations: 4n

5 masks: 4 x 5 = 20 depo’s45 = 1024 samples

Photograph of a 1” x 1”luminescent material library on Si after 20 quaternary depositions

(Left) Luminescent image of the same library after thermally processed under UV excitation.

Science 279, 1712 (1998)

Discrete Libraries vs Composition Spreads

Discrete libraries

•Discrete (separated) samples

•Various device libraries

•Semiconductor gas sensor libraries (electronic noses)

Composition spreads

•Details of compositional variation

•Mapping of phase diagrams

•BaTiO3-SrTiO3

•Magnetic metallic alloys(Ferromagnetic shape memory alloys)

Combinatorial Pulsed Laser Deposition Flange*

rotatable heater plate

x-y movableshutters/masks

drive chain

modular and compact 8” flange

*US provisional patent filed

Semiconductor Gas SensorsSemiconductive metal oxides change their

resistance in the presence of gases

• Advantages: Inexpensive, fast response to gases, etc…

• Problems: sensitivity, selectivity

• Use combinatorial technique (dopant library)

An electronic nose is an array of many different gas sensors coupled to a multiplexed pattern recognition system

2 mm

2 m

m

Pt(2.5%)

Resistance rangesat room temp.800 – 20M

100%

In2O3

(10%)

Pd (2.8%)

Pd +Pt (2.5%, 2.5%)

SnO2 +

In2O3+Pd+Pt(10%, 2.5%, 2.5%)

ZnO(10%)

In2O3+Pt (10%,2.5)

ZnO+Pd (10%, 2.8%)

ZnO+Pt (10%, 2.5%)

In2O3+Pd (10%, 2.8%)

ZnO+Pd+Pt(10%,2.5%2.5%)

WO3

(50%)

WO3+Pt (50%,2.5)

WO3+Pd (50%,2.8)

WO3+Pd +Pt(50%, 2.5%, 2.5%)

Gas Sensor Library Layout

•Au pattern

•16 different elements

•500Å each

•Deposition T= 500oC

23 mm

Discrete Gas Sensor Library

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

200

210

220

230

240

250

260

270

280

290

300

0

1

5

14

Temp

Time (second)

Rel

ativ

e c h

ang e

in r

e si s

t an c

eResponse of different sensor elements to exposure to gases

chloroform

100 ppmin air

formaldehyde benzene

formaldehyde

300 C

Moving shutter

Substrate (LaAlO3) at 800 C

Laser beam

BaTiO3

SrTiO3

Fabrication of in-situ deposited composition spreads

BaTiO3 or SrTiO3 target

ShutterSubstrate

HRTEM Micrograph of a Single Composition

Ba0.3Sr0.7TiO3

L. A. Bendersky,NIST

Scanning x-ray microdiffractometer(Bruker)

minimum beam Spot 50m

x-y-z motorized stage

area detector(2 and )

SrTiO3

BaTiO3

Substrate

50 m spot

Scanning x-ray microdiffraction

2 angles350 550

Y

Z

45.3

45.6

45.9

46.2

46.5

46.8

0.0 0.2 0.4 0.6 0.8 1.0

x in Ba1-xSrxTiO3

2

of (2

00) p

eak

(o )

BaTiO3 SrTiO3

2 angle

Scanning Diffraction Data

Zn0.4Mg0.6O

ZnO

(0001) Al2O3

(200) (cubic)

(0002) of hexagonal

(111) of cubic

(0006) of Al2O3

(200) of (cubic)

4530 35 40

2 Composition

change

2/ scan of Zn0.8Mg0.2O

(0002) of (hexagonal)

ZnO

Zn0.4Mg

0.6O

Sample

Coupling loop

Tip

Coaxial ¼

resonator

x-y-z stage Motion controller

Computer

f0

Q

Network analyzer

Rev. Sci. Inst., C. Gao et al., 69, 3846 (1998)Appl. Phys. Lett., I. Takeuchi et al., 71, 2026 (1997)

Scanning Microwave Microscope

L

For (Ba,Sr)TiO3

spread

Scanning Microwave Microscope

Dielectric const. vs. composition

0

200

400

600

800

1000

0.0 0.2 0.4 0.6 0.8 1.0Die

lect

ric

cons

tant 0.95 GHz

2.85 GHz

4.95 GHz

0

0.1

0.2

0.3

0.0 0.3 0.5 0.8 1.0

Los

s ta

ngen

t

BaTiO3 x in Ba1-xSrxTiO3 SrTiO3

Dielectric constant vs composition: temperature dependence

0

200

400

600

800

1000

0.0 0.2 0.4 0.6 0.8 1.0

Die

lect

ric

cons

tant

room temp.

130 C

0.95 GHz

Temperature (0C)

Die

lect

ric

cons

t.

BaTiO3 SrTiO3x in Ba1-xSrxTiO3

80 13030

700

900

500

Appl. Phys. Lett. 79, 4411 (2001)

Ba0.65Sr0.35TiO3

Frequency dispersion

0

0.02

0.04

0.06

0.08

0.0 0.2 0.4 0.6 0.8 1.0

Nor

mal

ized

die

lect

ric

cons

t. di

sper

sion

Room Temperature

BaTiO3 x in Ba1-xSrxTiO3

1GHz-5GHz)/1GHz

SrTiO3

Phonon soft mode and dielectric dispersion in (Ba,Sr)TiO3 films

• Dielectric dispersion is caused by softening/hardening of the phonon soft mode.

• The soft mode moves to the lower frequency range near Tc and results in increased dispersion.

• Compositions near Tc display

largest dispersion.400

600

800

1000

1200

1400

1600

1800

0.01 0.1 1 10 100

Ba0.3

Sr0.7

TiO3 Thin Film

r'

Freq.(GHz)

55K

135K

155K

195K

235K

T < Tc

Magnetic Metallic Alloys

Permanent magnets, eg. FexNdyBz

Half metals with high spin polarization for spintronics devices

Ferromagnetic shape memory alloys e.g. Ni2MnGa, Cu2MnGa

Scanning SQUID microscope is used to map magnetic properties.

UHV chamber -need to avoid oxygen and water

Magnetron co-sputtering

Natural Composition Spread using UHV non-confocalco-sputtering

Composition Spread of Metallic Alloys

Non-confocal (parallel) co-sputtering for creating natural ternary composition spreads.

x

Combinatorial UHV Co-sputtering (Pbase 1x10-9 Torr)

x

guns

distance between guns & substrate

spread profile

B

A C

A-B-C ternary phase diagram

A

B

C

A-B-C compositionspread

Compositional Mapping

i

Ni

Mn

Ga

From WDSanalysis

Ni

Mn

Ni2Ga3

Ni-Mn-Ga composition spread

Mapping of Ni-Mn-GaTernary Phase Diagram

UHV co-sputtering of 3 targets

The material must Be ferromagneticBe a shape memory alloy

Rapid characterization Scanning SQUIDCantilever librariesScanning x-ray diffract.

Ferromagnetic ShapeMemory Alloys

FerromagneticShapeMemory Alloys

ExampleNi2MnGa exhibits 6% strain in 1 kOe in bulk

Typical required field ~ kOe

1920 1940 1960 1980 20000.001

0.01

0.1

1

10

Mag

neti

c fi

eld

indu

ced

stra

in (

%)

Year of Discovery

Ni

Co-ferrite

Terfenol

FMSMA

History of Discovery: Magnetostrictive Materials

Composition SpreadDeposition

•Three targets: Ni, Mn, Ni2Ga3

•Substrate: Si•Thickness: 2500 Å•Insitu deposition w/physical mask •Lift off & annealed •Deposition or annealing temp 500 oC

Ni

Mn

Ni2Ga3

Scanning SQUID Microscope

Image from a SQUID Scan

y po

sitio

n (m

m)

x position (mm)

B field in nT

40 30 20 10

35

30

25

20

15

10

5

-1100 -680 -260 160 580 1000

15 20 25 30 35 40 45 50

60

50

40

30

20

col

row

-2.50e+007 0.00e+000 2.50e+007

rho1_25_x

100-150 emu/cc

50-70 emu/cc30-40 emu/cc

10-20 emu/cc

0 13 25 38 50 63 75

80

60

40

20

0

col

row

-2.50e+007 0.00e+000 2.50e+007

rho1_25

Scanning SQUID image of a Ni-Ni2Ga3-Mn spread wafer

Mn rich

Ni2Ga3 rich

Ni rich

Combinatorial Search of FMSMA: Mapping of Ferromagnetism

0

1

2

3

4

5

6

7

8

910

GaNi 0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Mn

50 100 150 200 250

M (emu/cc)

Ferromagnetic

Detection of Martensitic Transition Temperature

(Looking for Shape Memory Alloys)

-150 -100 -50 0 50 100 150

-120

-100

-80

-60

-40

-20

0

20

NiTi Cantilever

Capacitance Optical

Temperature (°C)C

anti

leve

r D

ispl

acem

ent (

um)

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

Lin

e P

osit

ion

(pix

els)

Comparison of optical and capacitance data for cantilever deflection with temperature.

Si

filmMonitor bendingand unbending

Side view of a cantilever

Composition Spread on Cantilevers

Three targets: Ni, Mn, Ni2Ga3

Micro machined cantilevers Alloy film thickness: 1m

Detection of structural phase transition by visual inspection

Measurement setup: Cantilever libraries

Vacuum line

LightsPt temperaturesensor

Colored lines on reverse side for reflection off of cantilevers

Defrosting line

Heating line

Cooling line

Compositions displaying Martensitic transition

Detection of Martensitic transition by visual inspection

“Movie” tracks the temperature change from room temp. to 200 C.

Each cantilever acts as a concave mirror with changing concavity.

Individualcantilever

Color lines are reflection of an image.

-50 0 50 100 150 200

Austenite Start Temp (0C)

0

1

2

3

4

5

6

7

8

9

10

GaNi0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Mn

Combinatorial Search of FMSMA: Composition Mapping of Martensites

I. Takeuchi, UMDONR MURI

SMA

0

1

2

3

4

5

6

7

8

9

10

GaNi 0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Mn

-50 0 50 100 150 200

Temp (0C)

Mapping of SMA and Magnetic Regions

FerromagneticSMA

0

1

2

3

4

5

6

7

8

9

10

GaNi 0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Mn

-50 0 50 100 150 200

Temp (0C)

Mapping of SMA and Magnetic Regions

microdiffraction along this line

Tracking the transition with micro-XRD as a function of composition

composition

inte

nsity

240

50

(220)A

(101)M(110)M

Ni39Mn51Ga10

Ni31Mn62Ga7

microdiffraction across the line on the spread

room temperature

0

1

2

3

4

5

6

7

8

9

10

GaNi 0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Mn

Martensites

Ferromagneticregions

Ni2Ga3

FerromagneticShapeMemory Alloys

Mapping of SMA and Magnetic Regions:summary

0

1

2

3

4

5

6

7

8

910

GaNi 0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Mn

Martensites

Ferromagneticregions

Ni2Ga3

Compositional regions that display martensites

Regions with average electron concentration 7.3-7.8

0 50 100 150 200 250 300 3500

100

200

300

400

500

600M

arte

nsit

e st

art

tem

pera

ture

(K

)

Magnetization (emu/cm3) at room temp

Saturation magnetization vs Martensite start temperature for various compositions on Ni-Mn-Ga spreads

University of MarylandK.-S. Chang R. D. VisputeM. Aronova S. E. LoflandO. Famodu F. C. WellstoodJ. C. Read M. WuttigW. Yang

ONR N000140010503, N000140110761NSF DMR0094265, DMR0076456

Support

Collaborators

The Second US-JAPAN Workshop on Combinatorial Materials Science

and Technology Winter Park, Colorado, Dec 9-11, 2002www.nrel.gov/usjapancombi2002